Development of materials which bond to enamel and dentin has revolutionized restorative and preventive dentistry. Pit and fissure sealants, a clinical application of the composite to etched surface bonding technology, has proven an effective preventive aid dramatically reducing caries in occlusal surfaces of primary and permanent posterior teeth. Dogma developed through microstructural and clinical studies states that failure of the bond between sealant and enamel is due to technique errors, most prominently the failure to adequately isolate the tooth from salivary contamination during the application procedure. This is a proposal to explore that dogma in light of our observations that in some circumstances salivary contamination of enamel may not compromise the bond of sealant to tooth (Hitt and Feigal, 1989; and Feigal, et al., 1990). We propose to rigorously test methods which appear to overcome the assumed moisture susceptibility of the sealant to enamel bond. This initiative is timely since NIDR has identified bonding to be a key area for dental research in the 1990's. "Efforts should be made to develop alternative bonding systems that are not technique sensitive." (NIDR Document, Broadening the Scope, pg. 36). Our lab data and clinical pilot data show that the use of a hydrophilic adhesive, Scotchbond (Sc), prior to sealant application overcomes negative effects of contamination. The proposed study will examine sealants bonded with and without bonding agents in the presence and absence of moisture. A variety of bonding agents will be compared in order to test whether hydrophilic or hydrophobic compounds afford the greatest benefit. All steps in the sealant method will be tested as to contamination sensitivity. Bond strength and dye leakage will be the in vitro success criteria, while clinical studies will measure long-term retention. Findings from this study may lead to new materials or techniques which would be less dependent upon strict clinical isolation techniques. The benefits of such changes would be: * increased possibilities for sealant use on patients who presently cannot comply with the strict moisture isolation methods (very young or handicapped patients). *improved sealant retention on occlusal surfaces of newly, or partially, erupted teeth. * increased opportunity for sealant use in parts of the world where clinical systems are not uniformly effective in affording strict isolation. * better acceptance of sealants by dental practitioners.